shibata



R. SHIBATA.

STEAM BOILER.

APPLICATION FILED AUG. 22. 1912.

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STEAM BOILER.

APPLICATION men we. 22. 1912.

Patmlted Aug. 1, 1916. 15. 2'.

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STEAM BOILER.

MPLICATION FILED AUG. 22. 1912.

PatentedAug. 1,1916.

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REIJI SHIBATA, F KOBE, JAPAN.

STEAM-BOILER.

Application filed August 2-2, 1912.

To all whom it may concern:

Be it known that I, Ii'EIJI SHIBATA, subject of the Emperor of Japan, residing at 438 Kanoda, Okuhirano, city of Kobe, Japan, have invented certain new and use ful In'iprovcments in Steam-Boilers, of which the following is a specification, reference being had therein to the accompanying drawing.

This invention relates to improvements in steam boilers and it consists essentially of the combination of a cylindrical boiler having furnaces only (hereinafter named the first boiler) with another cylindrical boiler having smoke tubes only (hereinafter named the second boiler), and a combustion chamber inclosed in fire-clay walls covered with iron sheets and asbestos plates, the boilers being connected by circulating water tubes, and a steam space in the second boiler only.

The principal objects of this invention are to obtain a boiler appropriate for high pressure steam and also to increase the efficiency and durability, to lessen damages due to explosion, to obviate the reduction of efficiency according to the age of the boiler, to minimize the repairing expenses for boilers of this kind, to narrow the floor space, and especially to obtain good efficiency in using smoky coal under forced draft. I

In describing this invention in detail, reference is made to the accompanying drawings, similar letters indicating similar parts, in which:

Figure 1 shows a front and sectional elevation of a steam boiler constructed according to this invention; Fig. 2 a side View of the boiler, partly in section; Fig. 3 a side view of a modification, partly in section; Figs. 4 to 6 are modifications shown diagrammatically.

In Figs. 1 and 2, A designates a three furnace boiler, for convenience named the first boiler, but this invention is applicable to boilers having a smaller or greater number of furnaces than three, and these furnaces may be arranged in any desired manner. 13 designates a smoke tube boiler, for convenience named the second boiler. These two boilers are connected by sets of circulating water tubes, one set aof which con nects the bottoms of the first and second boilers, and another set I) connects the top of the first boiler with the upper water space of the second boiler. o are the walls of the combustion chamber and will be made of Specification of Letters Patent.

back.

Patented'Aug. 1, 1916.

Serial No. 716,511.

fire-clay covered by iron sheets and asbestos plates. (Z and 6 show the positions of the scum valve and the check valve respectively. f and 9 show the positions of the blow-off valves of the second and the first boilers re-. spectively.

If desired,'two straight circulating water tubes 0 Z), having elliptical cross section and arranged at front and rear, may be provided to connect bottom of the second boiler with top of the first boiler, as shown in Fig. 3, instead of the circulating water tubes shown in Fig. 2.

The modification shown in Fig. 4, is similar to that shown in Fig. 1, except that the arrangement of the furnaces in the first boiler differs as illustrated.

Fig. shows a modification, in which a pair of such boilers as illustrated in Fig. 1 or Fig. 2 is arranged back to back, having a combustion chamber in common.

Fig. 6 shows a modification, in which the second boiler is arranged behind the first boiler.

In comparing this invention with the Scotch boiler, which may be considered as a combination of the Lancashire boiler with the multitubular boiler within one boiler shell, the following advantages are obtained under the present construction 1. In the Scotch boiler, the combustion chamber is supported by screw stays, dog stays and angle irons to provide the wet In such construction of the combustion chamber, although the sides supported by the screw stays may have some effect as one part of the heating surface when newly constructed, the conductivity of heat becomes reduced step by step by the scale deposited thereon. lVhen the scale is composed of salts only, it diminishes the chiciency when inch thick, and if it is composed of oil its intercepting action increases to 16 times that of salts. Hence,

these oarts of the combustion chamber after heated and The bot-tom of the combustion chamber becomes covered in a short time With a deposit, the deposition of Which interrupts the circulation of Water, and the shell Dlate be comes impaired especially by its oxidation. Therefore the combustion chamber of the Scotch boiler not only has little value as a heating surface, excepting the furnace plate, tube plate and top surface, but is the source of danger and of increasing expenses in treatment and i pairment. The top surface of the combustion chamber has considerable ei'liciency as a heating surface but if it is exposed above the water level it will be overccasienally cause dangerous explosion of boiler.

Smoky coals such as bituminous coal or brown coal, containing-11inch volatile matter, can not be burned completely Within so small a combustion chamber as that in the Scotch boiler and the volume ofpthe combustion chamber must be enlarged considerably to burn completely the carbon monoxid and free carbon produced from the coals. Under the construction herein illustrated and described, as the combustion chamber is outside or external of the boilers and is inclosed Within the fire-claywalls its volume may be increased easily as desired, and this construction has the following advantages Volatile matter may be burned completely in the large combustion chamber and thus increase the eiiiciency. (6) High pressure may be produced and increase the etiiciency. (0) Nearly all the ashes will deposit on the bottom of the com bustionchamber and this reduces the depo sition in the smoke tubes or the smoke box. (cl) Increase of durability. (6) Reduction of damages or dangerous explosions.

In the Scotch boiler, the group of smoke tubes is placed directly above the furnaces. In that construction, if scale has been deposited between the smoke tubes, the circulation of Water is impaired by the contraction of its passage and it eventually crushes the furnaces. first boiler has the furnaces only, the Water Copies of this patent may be obtained for Under my invention, as the 5 may circulate around the furnaces and the furnaces easily transmit the heat to the Water. This eliminates the crushing of the furnaces to a minimum and also minimizes the repairing expenses and increasing its durability. In the second boiler, as the smoke tubes are not exposed directly to the hot Water from the furnaces, they can trans mit tieir own heat completely to the Water and the tubes may be cleaned by a small quantity of cleaning chemicals without damage to the other parts of the boiler.

In this invention, as the, boiler. separated into two parts, the floor space required is very narrow and the parts may be arranged in any manner as desired. Either part of the boiler may be modified independently of another part, for xample, the pitch of the smoke tubes in the second boiler or the form of grate in the first boiler may be changed Without any effect on another part.

Having noW particularly described the nature of this said invention, and in what manner the same to be performed, I declare that What I claim is:

The combination with a cylindrical boiler having a plurality of furnaces only, of a cylindrical boiler having smoke tubes only, an external combustion chamber common to both boilers, the furnace boiler having a Water space around all the furnaces and no steam space and the smoke tube boiler formed with a steam space, circulating Water pipes connecting the bottom of one Water space of one boiler with the bottom of the Water space of the other boiler, and circulating Water pipes connecting the top Water space of one boiler with the top Water space'of the other boiler, substantially as described.

In testimony whereof I affix my signature in presence of two Witnesses.

REIJI SI-IIBA'IA. [Ls] Witnesses:

W. EBIHARAI-I, D. CLnTsU.

five cents each, by addressing the Commissioner of Patents. Washington, D. G. 

